How do I use my RS232 mini tester?

How do I use the RS232 mini tester from SFA?

Shop Floor Automations recommends a DB25 RS232 mini tester with every hardware order. We terminate our RS232 cabling with RJ45 connectors and have different adapters to tailor to each installation. Depending on your machine, you may require different pinouts on the adapters.

To test the correct pin-out in the cabling:

  • Connect the cable to the PC, Hub, or switchbox.
  • At the other end of the cabling, where the control would normally plug in, connect the tester. Without the tester plugged in the machine, you should see have “RD” lit and “TD” unlit.
  • For most applications, the other lights do not matter. If you plug the tester into the CNC machine control, you should then see “TD” lit.

If you have any variation of this, your machine will not communicate properly.

More about RS232 Cabling & Serial solutions:

From RS232 cables, RS232 Adapters, Honda Cables, RS232 Testers, & more, Shop Floor Automations has your custom cabling solutions! We can sell you 25 Foot to 100 Foot cables off the shelf, as well as make custom cables from 125 Feet up to 300 Feet in length.

  • Designed for Harsh Manufacturing Environments
  • Low Capacitance
  • Supports cable runs up to 300 feet with no data lost
  • 3 Levels of Shielding
  • 8 Conductors in the RS232 Serial Cable
  • 5-Year Warranty Against Defects
  • List of Supported Controls
  • Also, ask about RS232 adapters, FANUC cables, and more!


How are Grizzly Cables shielded?

How are Grizzly Cables shielded? A Grizzly Cable has four layers of shielding.

First, each wire is individually shielded with a polypropylene jacket. Second, an aluminum foil wraps around all of the pairs. Third, a metal braid shield is wrapped around the foil. Finally, a thick but flexible PVC jacket is wrapped around the metal braid.

The quality and strength of the shielding included with Predator Grizzly cables protect your data from RF noise and electrical interference. We highly recommend that you do not attempt to make your own Grizzly Cable.

More on how complex shop floor cabling is:

When it comes to running a machine shop floor, we know that the machinists and engineers, as well as those behind the scenes managing and in IT departments, are really smart, resourceful people. We are grateful when these individuals ask us for help in optimizing their production process, whether they shop with us over the phone or just buy items off of our store without prior consultation. We do notice, however, and we mean no disrespect, that some of these folks make a huge assumption that cabling is not a big decision – trust us that IT IS.

For those who prefer the traditional method of transmitting data via cables in their shop floors versus going wireless, there are many choices out there. Trying to save money by using commercial Ethernet cabling, or even worse, trying to use telephone cables, can result in massive issues on the shop floor. Sure, you save money short term, but the cons outweigh the pros.

This is a slowly changing industry and yesterday’s solutions may not work anymore, so that is why you have come to us. We are here to help your production thrive and to also only sell you services that you need. If a shorter cable costs less but is the best option for you, that is what we would recommend. Nothing more and nothing less.

Is a Grizzly cable just a simple Ethernet (CAT-5) cable?

Is a Grizzly cable just a simple Ethernet (CAT-5) cable?

No, a Grizzly cable is far different than commercial Ethernet cabling.

A CAT-5 cable is typically un-shielded, provides a balanced signal, and uses different wiring intended for a computer, as opposed to a CNC control.

The Grizzly Cable is shielded, with an ultra-low capacitance, uses unbalanced signals, and is wired for RS232 signals to be sent to and from CNC machines.

CAT-5 cables are unreliable, able to pick up RF noise very easily and have limitations regarding baud rate when running beyond RS232 specifications.

More about the complexity of serial cables for the manufacturing shop floor:

For those who prefer the traditional method of transmitting data via cables in their shop floors versus going wireless, there are many choices out there. Trying to save money by using commercial Ethernet cabling, or even worse, trying to use telephone cables, can result in massive issues on the shop floor. Sure, you save money short term, but the cons outweigh the pros.

This is a slowly changing industry and yesterday’s solutions may not work anymore, so that is why you have come to us. We are here to help your production thrive and to also only sell you services that you need. If a shorter cable costs less but is the best option for you, that is what we would recommend. Nothing more and nothing less.


Can I make my own Grizzly Cable?

Can you make your own Grizzly Cable? Sure, but it may not be worth the effort in research, soldering, testing, and cost of parts.

Normal serial cable is sensitive to interference and signal loss. We carefully engineered, manufactured and tested Grizzly cable to fit the needs of a shop floor environment.
Furthermore, your time is valuable and you have better things to do! Why not consult with experts?

Why it is worth your time to hire a professional technician:

With the popularity of YouTube, Reddit, WebMD, and similar sites, we are definitely a culture obsessed with DIY (AKA “do it yourself”). While this is great for cooking or hobbies, it is not necessarily the answer for everything pertaining to a job focused on manufacturing production. Here are the top 3 reasons you should hire a professional technician when implementing manufacturing hardware and software solutions versus going it alone:

Reason 1: Don’t assume the price tag to consult with a professional is going to be outlandish.

Reason 2: Hardware needs to be handled and wired a certain way.

Reason 3: Free up more time to get back to work, rather than struggling with something that is potentially foreign to you.

For example – manufacturing shop floor cabling (as you can read in this previous piece) are durable yet complex. It is best to let a technician install it for you, or tell you how to install and wire it over the phone, so you can ensure data will transfer correctly, you don’t potentially void a warranty, and that you also protect your investment.

What is causing my serial RS232 cable problems?

What could be causing my serial RS232 cable problems?

Here are some options, but we definitely recommend you contact our Support team.

Connecting pin one (earth ground) at both ends:
This creates a giant antenna, earth ground should only be connected at one end and generally at the device that is most grounded.

Using CAT5 cabling:

While CAT5 cable might work for a short while for RS232 communications, it is not designed for that application. CAT5 cable is twisted pair cabling for ethernet. Because it is designed for lower voltages and data that is checked packet-by-packet, CAT5 ethernet cable used for serial purposes can potentially cause a scrapped part by dropping data, short out the machine because of improper voltages and signals, and even crash a machine by sending bad data or omitting it. CAT5 cable is never recommended for RS232 communications. We recommend Predator Grizzly cable for RS232 serial communication because it is designed for this exact purpose and will prevent loss of data and interference issues.

Cable is not properly jumpered at CNC end:
Most CNCs will require jumpering of some sort. Most common is for pins 4 & 5 plus pins 6, 8 & 20.

Using unshielded cable:
Unshielded cable should never be used in a machine shop environment.

Twisted pair cabling not properly balanced:
If you use twisted pair, pins 2 and 3 can not be on the same pair. It is also recommended that you ground the other half of the pair for pins 2 and 3.

Cable with too few wires:
Most CNCs will only need TD, RD and SG, but some will require hardware handshaking and thus require more wires.

Improper positioning of cable:
Do not strap RS232 cabling to electrical conduit in the shop.

Incorrectly pinning out a DB9 to DB25 cable or adapter:
See the chart above, note that pins 2 & 3 are opposite from DB9 to DB25.

How is RS232 cabling pinned out, and what does each pin do?

How is RS232 cabling pinned out? What does each pin do?



The number preceding each signal name corresponds to the pin number defined in the standard.


  1.     Received Line Signal Detect (Carrier Detect)
  2.     Received Data
  3.     Transmitted Data
  4.     Data Terminal Ready
  5.     Signal Ground
  6.     Data Set Ready
  7.     Request to Send
  8.     Clear To Send
  9.     Ring Indicator


  1.     Protective Ground
  2.     Transmitted Data
  3.     Received Data
  4.     Request to Send
  5.     Clear To Send
  6.     Data Set Ready
  7.     Signal Ground
  8.     Received Line Signal Detect (Carrier Detect)
  9.     +P (for testing only)
  10.     -P (for testing only)
  11.     (unassigned)
  12.     Secondary Received Line Signal Detect
  13.     Secondary Clear To Send
  14.     Secondary Transmitted Data
  15.     Transmission signal element Timing
  16.     Secondary Received Data
  17.     Receiver Signal Element Timing
  18.     (unassigned)
  19.     Secondary Request To Send
  20.     Data Terminal Ready
  21.     Signal Quality Detector
  22.     Ring Indicator
  23.     Data Signal Rate Selector
  24.     Transmitter Signal Element Timing
  25.     (unassigned)

When selecting a vendor for your shop floor automation needs, it is important to select a company that is committed to service and support. Our client list continues to grow through recommendations from our customers, as well as our partners. You can speak to a real person over the phone with us, versus sending emails or leaving messages on a cell phone, then waiting for a response.

Read about our Support options!

How is RS232 different from parallel?

How is RS232 different from parallel?

In the past, most IBM PC and compatible computers were typically equipped with two serial ports and one parallel port. Although these two types of ports are used for communicating with external devices, they work in different ways.

A parallel port sends and receives data eight bits at a time over 8 separate wires. This allows data to be transferred very quickly; however, the cable required is bulkier because of the number of individual wires it must contain and cable distances are generally very short.

Parallel ports are typically used to connect a PC to a printer and are rarely used for much else. A serial port sends and receives data one bit at a time over one wire. While it takes eight times as long to transfer each byte of data this way, only a few wires are required. In fact, two-way (full duplex) communication is possible with only three separate wires – one to send, one to receive, and a common signal ground wire.

Interested in participating in a case study?

Shop Floor Automations believes in measurable results. Check out these case studies on how our solutions help out manufacturing shop floor operations!

We are always conducting case studies on our Manufacturing Solutions. We value input from our customers, as well as feedback. Participate in a case study.

What is RS232?

What is RS232? The RS232-C interface was developed for a single purpose. This purpose is stated by its title:

“Interface Between Data Terminal Equipment and Data Communications Equipment Employing Serial Binary Data Interchange.”

Every word in the title is significant: it describes the interface between a terminal (DTE) to a modem (DCE) for the transfer of serial data.

Short for Recommended Standard-232C, a standard interface approved by the Electronic Industries Association (EIA) for connecting serial devices. In 1987, the EIA released a new version of the standard and changed the name to EIA-232-D. And in 1991, the EIA teamed up with Telecommunications Industry Association (TIA) and issued a new version of the standard called EIA/TIA-232-E. Many people, however, still refer to the standard as RS232C or just RS232.

Almost all modems conform to the EIA-232 standard and most personal computers have an EIA-232 port for connecting a modem or other device. In addition to modems, many display screens, mice, and serial printers are designed to connect to an EIA-232 port. In EIA-232 parlance, the device that connects to the interface is called a Data Communications Equipment (DCE) and the device to which it connects (e.g., the computer) is called a Data Terminal Equipment (DTE).

The EIA-232 standard supports two types of connectors, a 25-pin D-sub type connector (DB25) and a 9-pin D-sub type connector (DB9). The type of serial communications used by PCs requires only 9 pins so either type of connector will work equally well.

Although EIA-232 is still the most common standard for serial communication, the EIA has recently defined successors to EIA-232 called RS422 and RS423. The new standards are backward compatible so that RS232 devices can connect to an RS422 port.

Learn more about our Serial and RS232 related solutions

Where did RS232 come from?

What is RS232 and what is the term’s history?

In the early 1960’s, a standards committee, today known as the Electronic Industries Association, developed a common interface standard for data communications equipment. At that time, data communications were thought to mean digital data exchange between a centrally located mainframe computer and a remote computer terminal, or possibly between two terminals without a computer involved.

These devices were linked by telephone voice lines and consequently required a modem at each end for signal translation. While simple in concept, the many opportunities for data error that occur when transmitting data through an analog channel, as it requires a relatively complex design.

It was thought that a standard was needed first to ensure reliable communication, and second to enable the interconnection of equipment produced by different manufacturers, thereby fostering the benefits of mass production and competition. From these ideas, the RS232 standard was born. It specified signal voltages, signal timing, signal function, a protocol for information exchange, and mechanical connectors.

If a proprietary or special high-speed transfer method is required by the CNC control, the customer may have to be upgraded to Predator DNC. Unlike the Editor, Predator DNC is designed to support proprietary and special high-speed transfer methods. Refer to our DNC Objects section for more details.

About RS232 Serial solutions we offer:

Our Serial Connect line is perfect for shop floor workers inclined to use a traditional RS232 cabling connection to machine tools. These products are compatible with new & legacy RS232 CNCs, serial equipment, the point of sale applications, & other mobile devices.

With options to link up via CAT5/6 Ethernet cables or direct ports to PCs, & even for new laptops with only USB connections, we can connect you. The USB-to-Serial converter is the perfect accessory for laptops computers that do not have a traditional 9pin RS232 port. Connect your CNC control to your computer using our RS232 serial cables & adapters – they are pinned & available in various lengths.

How to connect CNC Machines to laptop on Windows 7 or 8

How to connect CNC Machines to a laptop on Windows 7 or 8:

Because modern Laptops and PCs don’t come with Rs232 serial ports any longer, you will need to get a USB to RS232 “Industrial grade” adapter and the proper serial cable to connect from the USB to RS232 adapter to your CNC Machine.

More about this solution:

You may have tried the low-end USB to Serial Converter for your CNC and wonder why things don’t work.  Well, we are here to share the right solution to connect your CNC controls with your computer using USB.  We were there 5 years ago and finally found the one that works, every time, with 100% reliability.

This product is compatible with new and legacy RS232 devices and can be used with mobile, instrumentation, and point-of-sale applications as well. Our USB-to-Serial converter is the perfect accessory for laptop computers that don’t have a serial port. Support Windows 7 and 8, 32/64 bit operating systems. DB9 male connector for RS232.

  • Reliable USB to Serial converter
  • Compatible with Windows, plus new & legacy RS232 devices
  • Use with mobile, instrumentation, & point-of-sale applications
  • Great for laptop computers without a serial port
  • CNC Control Compatible

Call for more info on how to connect your CNC machines for the best communication at (877) 611-5825